Alexander believes that it is the "stealing" of Shylock's daughter Jessica that is the turning point in his behaviour. Originally, he says, "the contract with Antonio was, 'a merry bond', almost a joke meant to ingratiate himself with the Christians. But the loss of his daughter turns him to bitter hatred, which, once unleashed, gathers up all the long-suppressed anger for a string of slights and insults suffered."
Often ready to transpose the period of Shakespeare's plays - his Macbeth was set in a post-nuclear-holocaust future - Alexander has kept The Merchant in Renaissance Venice. "The play belongs to this setting for two very important reasons," he says. "The first is its approach to marriage. Both in Venice and Elizabethan England, marriage was a business contract tied to money and property, yet at the same time the radical idea of marrying for love was beginning to take hold. This was a contradiction that neither the play nor Shakespeare's contemporaries were able to resolve."
"Secondly, it's important to have a society where justice is really rough. If you put the play in a modern setting it becomes incredible that the courts would ever grant the flesh bond. But in a society where to be hung, drawn and quartered was legal, Shylock's bond does not seem out of place."
Alexander sees Renaissance Venice as a society poised between the modern capitalist world, in which charging interest for venturing capital is the norm, and the medieval world, in which the Catholic church held sway and "usury" was a sin. In this respect, Shylock represents the more modern outlook, and in the Birmingham Rep production he is very much a European Jew, someone who might expect to have been assimilated and accepted rather more than he has been.
Alexander says that The Merchant is not a problem play but one of welcome complexities and contradictions. "I hope audiences, particularly young people, will gain an understanding of how complex human beings are: that, for instance, the same people who can be extroadinarily unkind, even cruel, can also be daring, brave and loyal."
At Birmingham Rep until March 8 (box office: 0121 236 4455); Liverpool Royal Court March 18-22; Bradford Alhambra March 25-29; Norwich Theatre Royal April 8-12; Richmond Theatre April 15-19; York Grand Opera House April 22-26